This invention relates to indexable threading inserts for use in metalworking, and particularly to an indexable threading insert that may be mounted in a negative rake holder and yet have the insert cutting edges presented to the workpiece at a zero or positive rake angle.
Further, in the particular threading insert embodied by the present invention, a specific chip breaker groove is used with a threading insert.
Indexable threading and grooving inserts are known and find a wide variety of use throughout the metalworking industry. Indexable inserts for threading and grooving and the tool holder that receives such inserts should be designed so that the insert is accurately located and rigidly held on the tool holder when performing any work.
The inserts must usually be small and narrow in width and have a portion that overhangs the tool holder to do the threading. Under these condition, ideal arrangements for such inserts and tool holders are constantly being sought. While various types of threading and grooving combinations are known, one successful arrangement for such an insert and tool holder is described in applicant's own U.S. Pat. No. 3,754,309. Indexable inserts described by the patent have been in the market for several years, have enjoyed success in the marketplace and have become known by most people in the metalworking industry, specifically in the threading and grooving area. The cutting edges of the inserts can taken on various complex forms for threading operations while, also, being capable of taking a simple form for grooving operations.
Another type of indexable insert on the market, which is usually used for turning, boring and profiling work, but not for threading and grooving operations, is described by applicant's U.S. Pat. No. 3,399,442. These inserts describe an insert that can be used in a negative rake tool holder and yet present positive rake cutting edges to the workpiece. In some instances, as described by the patent, positive rake cutting conditions are preferable to negative rake cutting conditions.
Indexable inserts should, by their very nature, have as many cutting edges on the insert body as is possible. The threading and grooving indexable inserts described above have only two cutting regions on the body of the insert. It is proposed by this application to make an indexable threading insert similar to the threading and grooving inserts described above, but the threading insert body will have four cutting regions instead of only two cutting regions as was previously possible.